SEMICONDUCTOR DEVICE AND SEMICONDUCTOR MANUFACTURING METHOD
One atomic layer of Si atoms 3 is grown on an Si-terminated SiC surface 1a having an Si polar face, and one atomic layer of C atoms 5 is further grown thereon. Then, Si and C are supplied to form an SiC layer. The surface of the SiC layer thus grown is a C polar face opposite to the Si polar face. That is, according to the above-described step, it is possible to grow an SiC polarity-reversed layer 1x having a C polarity on an SiC layer 1 having an Si polarity, with one atomic layer of an Si intermediate layer b interposed therebetween. Consequently, it is possible to provide a technique to reverse the polarity of SiC on the surface.
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The present invention relates to a semiconductor device and, more particularly, to a polarity control technique used for a semiconductor device formed on an SiC layer.
BACKGROUND ARTSiC has extremely high thermal conductivity, and an electrically conductive substrate and an electrically insulating substrate made of SiC are available. In addition, SiC is characterized by being close in lattice constant and thermal expansion coefficient to AlN and GaN-based group III nitrides, and by having polarities like the group III nitrides. A study is being made actively, in order to realize high-performance light-emitting diodes, laser diodes, transistors, optoelectronic integrated devices, and the like that utilize one or both of a group III nitride and SiC by growing a high-quality AlN or GaN-based group III nitride on an SiC substrate. SiC is also relatively close in lattice constant to ZnO-based materials which are group II oxides. Hence, a study is being made to apply SiC also as a group II oxide substrate.
SiC and a group III nitride are characterized in that Si-N bonds and C-group III metal (Al or Ga) bonds formed therebetween are strong. Consequently, SiC has the nature that the polarity control of a group III nitride grown on an SiC substrate is possible. That is, Si and N combines with each other in an SiC (0001) Si polar face in which the bonding hands of Si perpendicularly project to the surface thereof. As a result, the grown group III nitride has a structure in which bonds of group III atoms project perpendicularly, i.e., has a group III polar face. Conversely, C and a group III metal combine with each other in an SiC (000-1) C polar face in which the bonding hands of C perpendicularly project to the surface thereof. As a result, the grown group III nitride has a structure in which bonds of nitrogen atoms perpendicularly project, i.e., has an N (nitrogen) polar face. The same holds true for a group II oxide. That is, since an Si—O bond is strong, a group II polar face grows on the Si polar face and a group II oxide having an O polar face grows on the C polar face.
In an ordinary device, crystal polarities (or orientations) are desirably unified into one polarity across the entire surface of a substrate. However, in a certain type of device, for example, a second-order harmonic generation element which is one of nonlinear optical elements, regions in which a polarity is periodically reversed in the traveling direction of light are artificially introduced, thereby achieving quasi-phase matching and realizing extremely superior characteristics. In addition, if the characteristics of a device, such as the threshold voltage of a field-effect transistor, can be controlled by the polarity of a surface and an opposite polarity can be made to coexist in the surface, it is possible to use two types of transistors having significantly different threshold voltages. Consequently, the freedom of integrated circuit design improves greatly. These devices and integrated circuits cannot be fabricated, however, if polarities are unified into one polarity within a substrate plane.
Non-patent document 1: Chowdhury A, Ng H M, Bhardwaj M, et al. “Second-harmonic generation in periodically poled GaN” APPLIED PHYSICS LETTERS 83 (6): 1077-1079 AUGUST 11 (2003).
DISCLOSURE OF THE INVENTION Problems to be Solved by the InventionOn a substrate made of sapphire having no polarities unlike SiC, there is fabricated a polarity-reversed structure by taking advantage of the polarity of an obtained group III nitride being different depending on growth conditions or the surface treatment conditions of the substrate. That is, the group III nitride is first grown under growth conditions whereby the nitride has a Ga polarity, and then a group III nitride having a Ga polarity is removed by etching away unnecessary portions of the group III nitride, thereby exposing the sapphire substrate. Next, the group III nitride is grown under growth conditions whereby an opposite N polarity is formed. Thus, it is possible to grow a group III nitride having an opposite N polarity in a portion where the sapphire substrate is exposed (a group III nitride having a Ga polarity grows in a portion where the group III nitride having a Ga polarity has already been formed, while inheriting the polarity of the underlying group III nitride). As a result, a structure in which a group III nitride having an opposite polarity is mixed in can be artificially formed on a substrate surface. Such an artificially polarity-reversed structure, in which the substrate itself is nonpolar, can be realized on a sapphire substrate where the polarity of a group III nitride that grows thereon can be selected depending on growth conditions. In the case of a substrate made of SiC, however, it is not possible to adopt this method since the polarity of the group III nitride that grows on the substrate is fixed by the polarity of the substrate, as described above.
An object of the present invention is to provide a technique to form an SiC layer having a polarity opposite to the polarity of an SiC substrate, a group III nitride layer, or a group II oxide on a surface of the SiC substrate, thereby allowing the SiC layer having an opposite polarity, the group III nitride layer, and the group II oxide layer to coexist on the SiC substrate.
Means for Solving the ProblemsIn the (0001) Si polar face of 4H-, 6H- or 15R-SiC (a (111) Si polar face in the case of 3C-SiC), the bonding hands of Si perpendicularly project to a surface. If one atomic layer (referred to as an “intermediate layer”) of Si is grown on this Si polar face of SiC, Si—Si bonds are formed. As a result, it is possible to realize a surface structure in which Si bonds obliquely project out of the surface. By combining carbon with this surface structure, the carbon is caused to combine with three Si bonding hands. Consequently, the surface structure is formed into a surface equivalent to the C polar face of SiC in which the bonding hands of carbon project perpendicularly. By continuing SiC growth on this surface, it is possible to form an SiC layer having an oppositely-polarized C polar face on the Si polar face of SiC through the intermediate layer. In addition, by growing a group III nitride or a group II oxide on this C polar face of SiC using a usual method, it is possible to grow a group III nitride having an N polar face or a group II oxide having an O polar face.
By combining nitrogen with the surface structure in which Si—Si bonds are formed and consequently Si bonds obliquely project out of the surface, the nitrogen is caused to combine with three Si bonding hands. Consequently, the surface structure is formed into a surface equivalent to the N polar face of the group III nitride in which the bonding hands of nitrogen project perpendicularly. If a group III nitride is grown on this surface, the nitride grows with an N polar face retained. Thus, it is possible to obtain a group III nitride having an N polar face the polarity of which is opposite to a polarity expected in usual growth on SiC having an Si polar face.
By combining oxygen with the surface structure in which Si—Si bonds are formed and consequently Si bonds obliquely project out of the surface, the oxygen is caused to combine with three Si bonding hands. Consequently, the surface structure is formed into a surface equivalent to the O polar face of the group II oxide in which the bonding hands of oxygen project perpendicularly. If a group II oxide is grown on this surface, the oxide grows with an O polar face retained. Thus, it is possible to obtain a group II oxide having an O polar face the polarity of which is opposite to a polarity expected in usual growth on SiC having an Si polar face.
In principle, polarity reversal takes place as long as the number of Si insertion layers is an odd number and, therefore, it is possible to use an arbitrary odd number of Si intermediate layers. Due to a large lattice mismatch between Si and SiC, however, defects attributable to the lattice mismatch occur if an Si intermediate layer thicker than necessary is introduced. Consequently, the crystallinity of a polarity-reversed layer formed on the intermediate layer degrades. In addition, if the thickness of the Si intermediate layer increases depending on growth conditions, Si does not grow in a layer-shaped manner but grows in an island-shaped manner. Care should therefore be exercised since there arises the problem of inability to control the number of Si layers for the substrate as a whole (the thickness increases more largely in island-shaped portions than in layer-shaped portions, that is, thicknesses, i.e., polarities cannot be unified within a plane).
As an alternative, Si of an intermediate layer is intentionally grown thick, in order to cause polarity information held by SiC to disappear in the vicinity of the surface of the layer, thereby placing the layer in a state of as if being equivalent to the (111) face of Si having no polarities. Then, by controlling the growth conditions of SiC, a group III nitride or a group II oxide on the Si(111) face, it is possible to adopt a method for growing layers having arbitrary polarities. In this case, there is no need to strictly control the number of Si layers and, therefore, it is possible to simplify the process of forming intermediate layers. This means, however, that polarities are controlled by the growth conditions of the SiC, the group III nitride or the group II oxide. Accordingly, there is the possibility that some regions having a polarity opposite to an intended polarity mixes with the intermediate layer. In addition, the crystallinity of Si formed thick on SiC as described above cannot be said to be satisfactory for reasons of lattice mismatch. Thus, the quality of a crystal grown on this thick Si is sacrificed. The intermediate layer can be used with no difficulty for the fabrication of a device, such as a nonlinear optical element, insensitive to crystallinity. The intermediate layer is somewhat unsuitable, however, for such devices as a light-emitting diode, the crystallinity of which cause remarkable effects on the performance thereof.
As the intermediate layer, it is possible to use a material consisting primarily of a group IV element, having excellent affinity for SiC which is a group IV-IV compound, and having no polarities, i.e., a material consisting primarily of Si, Ge, C or the like. Use of pure Si is desirable from the viewpoint of simplifying film-forming apparatus. It is also possible, however, to use mixed crystals, such as SixGel-x with which Ge or the like is mixed, in order to facilitate the laminar growth of an intermediate layer. Since the better the crystallinity of an intermediate layer is, the better the quality of a polarity-reversed layer in an upper portion of the intermediate layer can be made, a composition or a thickness, whereby the best crystallinity can be obtained, may be selected according to a film-forming method. It is also possible to perform n-type doping, p-type doping, or the like, in order to provide the intermediate layer with a conductive property. Although in the description given above, an explanation has been made by taking, as an example, reversal from an Si polar face to a C polar face (or to an N polar face or an O polar face) by an Si intermediate layer, completely the same logic holds true with a C intermediate layer and a C polar face. Thus, there is obtained a total of four variations of reversal.
Advantages of the InventionAccording to the present invention, it is possible to fabricate a structure including polarity-reversed regions within a plane and comprised of SiC, a group III nitride and a group II oxide on an SiC polar face, with ease and precision. The present invention is applicable to a wide variety of fields, including, in particular, a quasi-phase matched nonlinear optical device and a field-effect transistor integrated circuit based on a group III nitride and a group II oxide.
1: SiC substrate, 1b: Intermediate layer, 1e: C atom layer, 1x: SiC layer, 3: Si atom, 5: C atom, 23b: Polarity-reversed layer, 23a: Polarity-unreversed layer.
BEST MODE FOR CARRYING OUT THE INVENTIONHereinafter, an explanation will be made of a semiconductor technology in accordance with embodiments of the present invention while referring to the accompanying drawings.
First, an explanation will be made of a semiconductor device and a semiconductor manufacturing method in accordance with a first embodiment of the present invention.
Strictly speaking, polar faces refer to the (0001) face and the (000-1) face only. However, a face inclined several degrees from the (0001) face, for example, can be regarded as an Si polar face. Even in the case of a face, such as a (03-38) face or a (0-33-8) face, inclined several tens of degrees from the (0001) face or the (000-1) face, the former is closer to the (0001) face which is an Si polar face and the latter is closer to the (000-1) face which is a C polar face. Accordingly, in the present specification, these faces are also included in the aforementioned polar faces as polar faces in a broad sense. A face opposite in polarity to the (0001) face is referred to as the (000-1) face, and a face opposite in polarity to a face inclined certain degrees from the (0001) face is referred to as a face inclined at a certain angle from the (000-1) face.
On the other hand, faces, such as (11-20) and (1-100) faces, completely perpendicular to the (0001) face are nonpolar faces for which polarities cannot be defined. These faces are therefore not referred to in the present specification.
As described above, since a bond between Si and N and a bond between C and a group III metal are strong, Si combines with N on an Si polar face if a group III nitride is grown on SiC. The group III nitride thus grown consequently has a structure in which bonding hands of group III atoms project perpendicularly. That is, the group III nitride has a group III polar face. In the present specification, the group III polar face is referred to as an identical polarity in contrast to an Si polar face, and an N polar face is referred to as an opposite polarity. Likewise, for a group II oxide, the group II polar face is referred to as an identical polarity in contrast to an Si polar face, and an O polar face is referred to as an opposite polarity.
First, an SiC substrate 1 having a (0001) Si polar face is prepared, and a surface treatment for the substrate to have a clean surface is performed. As illustrated in
Next, as illustrated in
In the above-described growth steps, it is important to precisely control the thickness of the Si intermediate layer 1b on the SiC surface 1a, so that the intermediate layer is formed of an odd number of layers. Accordingly, it is preferable to perform growth using surface-sensitive measuring means, such as electron beam diffraction, X-ray photoemission spectroscopy (XPS), or Auger electron spectroscopy, in the process of depositing the intermediate layer 1b, while observing a surface coverage and the like in real time. Note that, once conditions are fixed, it is possible to precisely deposit an intermediate layer composed of an odd number of atomic layers by controlling a supply rate and a supply time, without conducting real-time observations by these means.
In addition, since the intermediate layer 1b is thermodynamically unstable in initial stages of its growth and the subsequent growth of SiC, the intermediate layer needs to be grown in a state of being off from thermal equilibrium. A molecular beam epitaxy (MBE) method is one of the optimum methods in the sense that a nonequilibrium state is realized and the above-described real-time observation is possible. Considering mass productivity and the like, however, a vapor-phase epitaxy (VPE) method is also an effective method, though not capable of real-time observation. In layer growth on the intermediate layer 1b, it is important to set temperature lower than the usual growth temperature of SiC, in order to prevent atomic exchange or diffusion from occurring in the vicinity of a surface. For example, if the temperature of a step of supplying C onto Si—Si bonds is too high, Si switches positions with C in the surface, i.e., the Si intermediate layer 1b is carbonized, and SiC having a polarity identical to that of underlying SiC 1 is formed. That is, the intermediate layer disappears and thus the layer growth results in mere SiC homoepitaxial growth of an identical polarity.
For the thickness of the intermediate layer 1b, it is possible to use an odd number of layers equal to or greater than one, as is shown by a crystal structure. However, if an Si layer thicker than necessary is introduced, a defect attributable to the lattice mismatch occurs due to a large lattice mismatch between Si and SiC. Thus, the crystallinity of an SiC polarity-reversed layer grown on the Si layer degrades. In addition, Si does not grow in a layer-shaped manner but grows in an island-shaped manner, depending on growth conditions. Consequently there arises the problem that it is not possible to control the number of layers of Si for the substrate as a whole (the intermediate layer 1b becomes thicker in island-shaped portions than in other portions). Accordingly, the intermediate layer 1b is preferably made as thin as possible, and is preferably made of one or three layers, or five layers or so. According to a semiconductor manufacturing method in accordance with the present embodiment, it is also possible to precisely deposit an SiC layer (polarity-reversed layer) having a C polarity on an SiC layer having an Si polarity through C—C bonds formed by an odd number of C intermediate layers (one layer is shown here by way of example), as illustrated in
In the present embodiment, although an explanation has been made of an example in which crystal growth is initiated from a perfect Si-terminated face, it is also possible to initiate crystal growth from a state in which Si is partially adsorbed to the Si-terminated face. In an MBE method, a method for removing impurities, such as oxides, by performing high-temperature heating while applying Si irradiation is used for the cleaning of the Si polar face of SiC. A cleaned SiC surface available by this method is in a state in which a ⅓ atomic layer of Si is excessively adsorbed to an Si-terminated face, as illustrated in
An important point in the above-described polarity reversal technique using an intermediate layer composed of an odd number of atomic layers is that atoms of the intermediate layers take the form of a four-coordinate structure. For example, if a C intermediate layer is used and if the layer takes the form of a three-coordinate structure, i.e., a graphite structure, it is difficult to grow satisfactory SiC, group III nitride or group II oxide on the intermediate layer, not to mention polarity reversal.
Next, a semiconductor growth method in accordance with a first modified example of the above-described first embodiment will be described while referring to
supplying N (or O) to a substrate;
forming one atomic layer 1d of nitrogen (or oxygen);
subsequently supplying N and a group III element (or O and a group II element) to grow a group III nitride (or a group II oxide); and
thereby growing an AlN layer 7 (or a GaN layer, a ZnO layer, or the like) having a polarity opposite to that of SiC 1, as illustrated in
II oxide having an O polarity), as illustrated in
Next, an explanation will be made of a semiconductor device and a manufacturing method thereof in accordance with a second embodiment of the present invention. In the first embodiment, polarity reversal is achieved using the intermediate layer 1b composed of an odd number of atomic layers (formed as thin as possible and composed preferably of 1 or 3 layers, or so). Alternatively, the manufacturing method of the second embodiment is characterized by including the steps of:
intentionally growing the Si of an intermediate layer thick, in order to eliminate the effects of a polarity held by SiC;
simulatively placing a surface of the intermediate layer in a state of being equivalent to an Si(111) face having no polarities; and
growing a layer having an opposite polarity by adjusting the growth conditions of SiC to be grown on this surface.
First, an SiC substrate 11 having a (0001) Si polar face is prepared, and a surface treatment for the substrate to have a clean surface is performed. Next, Si is supplied onto this substrate 11 and a Si intermediate layer 1b having a thickness of, for example, 20 nm is heteroepitaxially grown, as illustrated in
In this case, unlike the first embodiment, there is no need to strictly control the number of layers of Si. Accordingly, the manufacturing method of the second embodiment has the advantage of being able to reduce constraints on the formation process of the intermediate layer 11b and significantly simplify steps. However, since SiC of either polarity can grow on the Si(111) face having no polarities, there is the possibility that some amount of SiC having a polarity opposite to an intended polarity mixes with SiC having the intended polarity. In addition, since a thick layer of Si having a greatly-differing lattice constant is introduced, it is increasingly difficult to upgrade the quality of the SiC layer 11c having an opposite polarity as much as in the first embodiment that uses an extremely thin intermediate layer. Since the process is simple, however, the manufacturing method is extremely effective for application to devices in which requirements for the quality of layers having an opposite polarity are not severe, for example, to nonlinear optical elements or the like, in that this thick Si layer can be utilized for the intermediate layer. The lower limit of the thickness of the intermediate layer 11b depends on how thick the intermediate layer 11b should be, to be able to remain after the growth of SiC thereon. That is, a process of Si carbonization (conversion into SiC) is generally used before the growth of SiC on Si. If the Si intermediate layer 11b is too thin, all intermediate layers are carbonized. Carbonized regions reach the SiC substrate 11 and the carbonized layers inherit the polarity of the SiC substrate 11. Thus, SiC growth results in mere homoepitaxial growth in which a polarity is not reversed.
On the other hand, the upper limit of the thickness of the intermediate layer depends on the resolution of lithography used in subsequent device fabrication. That is, if the Si intermediate layer 11b is too thick, deeper etching becomes necessary in order to remove partial regions of the Si intermediate layer 11b. Consequently, there are the problems of aspect ratio constraints in etching treatment and a degradation in the accuracy of minimum processing dimensions within the face concerned. For example, assuming a minimum processing dimension of 0.5 μm, then the thickness of the Si intermediate layer 11b is desirably 0.1 μm or smaller, i.e., 100 nm or smaller. Note that if a thick intermediate layer is used, the composition thereof can be an arbitrary composition containing one of Si, C, and Ge. As far as polarity reversal by the thick intermediate layer described here is concerned, the intermediate layer need not necessarily take the form of a four-coordinate structure. In order to maintain the crystallinity of a polarity-reversed layer to be satisfactory, however, it is desirable to allow the intermediate layer to have orientation of at least some sort. More desirably, the intermediate layer is epitaxially grown with respect to SiC. Even more desirably, the intermediate layer is epitaxially grown into one of a diamond structure, a zinc blende structure and a wurtzite structure. From the above-described point of view, it can be said that an epitaxially-grown layer of Si or Si1-xGex having a diamond structure is best suited as the intermediate layer.
Next, an explanation will be made of a semiconductor growth method in accordance with a first modified example of the second embodiment. The semiconductor growth method in accordance with the present modified example is the same in process, up to the step of depositing the intermediate layer 11b, as the SiC semiconductor growth method in accordance with the second embodiment. Unlike the second embodiment, however, SiC is not grown but a group III nitride (or a group II oxide) is grown after the growth of the intermediate layer (
Next, a semiconductor growth method in accordance with modified examples of the first and second embodiments will be described, while referring to
Next, an explanation will be made of a semiconductor device and a manufacturing method thereof in accordance with a third embodiment of the present invention.
Next, an explanation will be made of a semiconductor device and a manufacturing method thereof in accordance with a fourth embodiment of the present invention.
As described above, according to the semiconductor device and the manufacturing method thereof in accordance with the present embodiment, it is possible to realize arbitrary structures, including a structure in which AlN layers having different polar faces are periodically formed in one direction within a plane of the substrate. Note that an irregularity occurs on a surface of the structure, as illustrated in
Next, an explanation will be made of a semiconductor device and a manufacturing method thereof in accordance with a fifth embodiment of the present invention.
It is also possible to fabricate a polarization reversal structure of a group III nitride or a group II oxide, as illustrated in
Next, an explanation will be made of a semiconductor device having a waveform conversion function fabricated by applying the above-described fourth embodiment, as a technology in accordance with the sixth embodiment of the present invention.
As illustrated in
Next, as illustrated in
Next, a semiconductor device fabricated by applying the fourth embodiment will be described as a seventh embodiment of the present invention, while referring to drawings.
As illustrated in
Next, as modified examples of the seventh embodiment of the present invention, it is possible to fabricate: such a device as described above and illustrated in
The device of
In
As a matter of course, it is also possible to fabricate a device in which the group III nitride is replaced with a group II oxide. In addition, the elements are not limited to a MOSFET and a HEMT but can be arbitrary elements, such as diodes, light-emitting diodes, laser diodes, or bipolar transistors. Since SiC, a group III nitride and a group II oxide have strong polarities and the optimum polarity differs depending on the type of device, a technique to integrate elements of both polarities on a single substrate is extremely useful, as described in the present embodiment. For the fabrication of a polarity-reversed region, it is possible to freely combine the first to fifth embodiments and the modified examples thereof. An SiC device is generally fabricated on a face inclined two to nine degrees from a (0001) face or a (000-1) face. Accordingly, it is possible to utilize a face of 4H-SiC inclined four degrees in a <11-20> direction from the (0001) face, as an SiC substrate, in the case of, for example, the device illustrated in
A semiconductor technology in accordance with the present invention is also applicable to, for example, the fabrication of an optical device based on a group III nitride or a group II oxide, an optical integrated circuit in which SiC electronic devices are integrated, a group III nitride, a group II oxide, and an SiC micromachine (MEMS), in addition to a nonlinear optical device and an integrated circuit. Furthermore, using the same technique, it is also possible to fabricate a structure in which polarity-reversed and polarity-unreversed regions coexist, not only for group III nitrides and group II oxides but also for arbitrary semiconductors and dielectric materials capable of growth while inheriting the polarity of SiC.
INDUSTRIAL APPLICABILITYAccording to the present invention, it is possible to fabricate an SiC-based polarity-reversed layer with ease and precision. The present invention is applicable to a variety of fields, including, in particular, a quasi-phase matched nonlinear optical device and a HEMT integrated circuit.
Claims
1. A semiconductor device comprising:
- a first SiC layer having a first polar face;
- an intermediate layer formed by being deposited on the first SiC layer and comprised of an Si layer or a C layer; and
- a second SiC layer formed by being deposited on the intermediate layer and having a second polar face opposite to the first polar face.
2. A semiconductor device comprising:
- a first SiC layer having a first polar face;
- an intermediate layer formed by being deposited on the first SiC layer and comprised of an Si layer or a C layer; and
- a first group III nitride layer or group II oxide layer formed by being deposited on the intermediate layer and having a second polar face opposite to the first polar face.
3. A semiconductor device comprising:
- a first SiC layer having a first polar face;
- an intermediate layer formed by being deposited on the first SiC layer and comprised of an Si layer or a C layer;
- a second SiC layer formed by being deposited on the intermediate layer and having a second polar face opposite to the first polar face; and
- a first group III nitride layer or group II oxide layer deposited on the second SiC layer and having a polar face identical to the second polar face.
4. The semiconductor device according to claim 1, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, and a third SiC layer having a polar face identical to the first polar face is formed in the region.
5. The semiconductor device according to claim 1, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, and a second group III nitride layer or group II oxide layer having a polar face identical to the first polar face is formed in the region.
6. The semiconductor device according to claim 1, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, a third SiC layer having a polar face identical to the first polar face is formed in the region, and a second group III nitride layer or group II oxide layer having a polar face identical to the first polar face is further formed on the third SiC layer.
7-8. (canceled)
9. The semiconductor device according to claim 1, characterized in that the intermediate layer is an odd number of atomic layers.
10. The semiconductor device according to claim 1, characterized in that the intermediate layer is one atomic layer.
11. The semiconductor device according to claim 1, characterized in that the thickness of the intermediate layer is 100 nm or smaller.
12. The semiconductor device according to claim 1, characterized in that the first polar face is the (0001) Si polar face of 4H-, 6H- or 15R-SiC or the (111) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (0001) Si polar face or the (111) Si polar face is no larger than 10 degrees.
13. The semiconductor device according to claim 1, characterized in that the first polar face is the (000-1) C (carbon) polar face of 4H-, 6H- or 15R-SiC or the (-1-1-1) C polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (000-1) C polar face or the (-1-1-1) C polar face is no larger than 10 degrees.
14. The semiconductor device according to claim 2, characterized in that the first polar face is the (0001) Si polar face of 4H-, 6H- or 15R-SiC or the (111) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (0001) Si polar face or the (111) Si polar face is no larger than 10 degrees, and the second polar face is the (000-1) nitrogen or O (oxygen) polar face of a group III nitride layer or a group II oxide layer, or a face the deviation of which in a plane direction from the (000-1) face is no larger than 10 degrees.
15. The semiconductor device according to claim 2, characterized in that the first polar face is the (000-1) C polar face of 4H-, 6H- or 15R-SiC or the (-1-1-1) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (000-1) C polar face or the (-1-1-1) Si polar face is no larger than 10 degrees, and the second polar face is the (0001) group III or group II polar face of a group III nitride layer or a group II oxide layer, or a face the deviation of which in a plane direction from the (0001) face is no larger than 10 degrees.
16. A waveguide-type quasi-phase matched wavelength conversion element comprising:
- a first optical waveguide structure formed on a first SiC layer having a first polar face and comprised of a first group III nitride or a group II oxide having a polar face identical to the first polar face; and
- a second optical waveguide structure comprised of a second group III nitride or group II oxide, formed by being deposited, through an intermediate layer formed by being deposited on the first SiC layer and comprised of an Si layer or a C layer, on the intermediate layer and having a polar face opposite to the first polar face;
- wherein the first optical waveguide structure and the second optical waveguide structure are spatially arranged and the optical waveguides of both the first and second optical waveguide structures are connected to each other.
17. An integrated circuit comprising:
- a first semiconductor device formed on a first SiC layer having a first polar face and comprised of SiC, a group III nitride or a group II oxide having a polar face identical to the first polar face; and
- a second semiconductor device comprised of SiC, a group III nitride or a group II oxide, formed by being deposited, through an intermediate layer formed by being deposited on the first SiC layer and comprised of an Si layer or a C layer, on the intermediate layer and having a polar face opposite to the first polar face.
18. A semiconductor device comprising:
- a first SiC layer having a first polar face;
- an intermediate layer formed by being deposited on the first SiC layer and comprised of an SixGe1−x layer; and
- a second SiC layer formed by being deposited on the intermediate layer and having a second polar face opposite to the first polar face.
19. The integrated circuit according to claim 17, characterized in that the first semiconductor device and the second semiconductor device are high electron mobility transistors (HEMTs) having different threshold values.
20. The integrated circuit according to claim 17, characterized in that the first semiconductor device and the second semiconductor device are SiC MOSFETs having different threshold values.
21. The integrated circuit according to claim 17, characterized in that the first semiconductor device is an SiC MOSFET and the second semiconductor device is a high electron mobility transistor (HEMT).
22. A semiconductor substrate comprising:
- a first SiC layer having a first polar face;
- an intermediate layer formed by being deposited on the first SiC layer and comprised of an Si layer or a C layer; and
- a second SiC layer formed by being deposited on the intermediate layer and having a second polar face opposite to the first polar face.
23. A semiconductor substrate comprising:
- a first SiC layer having a first polar face;
- an intermediate layer formed by being deposited on the first SiC layer and comprised of an Si layer or a C layer; and
- a first group III nitride layer or group II oxide layer formed by being deposited on the intermediate layer and having a second polar face opposite to the first polar face.
24. A semiconductor substrate comprising:
- a first SiC layer having a first polar face;
- an intermediate layer formed by being deposited on the first SiC layer and comprised of an Si layer or a C layer;
- a second SiC layer formed by being deposited on the intermediate layer and having a second polar face opposite to the first polar face; and
- a first group III nitride layer or group II oxide layer formed by being deposited on the second SiC layer and having a polar face identical to the second polar face.
25. The semiconductor device according to claim 2, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, and a third SiC layer having a polar face identical to the first polar face is formed in the region.
26. The semiconductor device according to claim 3, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, and a third SiC layer having a polar face identical to the first polar face is formed in the region.
27. The semiconductor device according to claim 2, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, and a second group III nitride layer or group II oxide layer having a polar face identical to the first polar face is formed in the region.
28. The semiconductor device according to claim 3, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, and a second group III nitride layer or group II oxide layer having a polar face identical to the first polar face is formed in the region.
29. The semiconductor device according to claim 2, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, a third SiC layer having a polar face identical to the first polar face is formed in the region, and a second group III nitride layer or group II oxide layer having a polar face identical to the first polar face is further formed on the third SiC layer.
30. The semiconductor device according to claim 3, wherein there is a region on the first SiC layer in which the intermediate layer does not exist, a third SiC layer having a polar face identical to the first polar face is formed in the region, and a second group III nitride layer or group II oxide layer having a polar face identical to the first polar face is further formed on the third SiC layer.
31. The semiconductor device according to claim 2, characterized in that the intermediate layer is an odd number of atomic layers.
32. The semiconductor device according to claim 3, characterized in that the intermediate layer is an odd number of atomic layers.
33. The semiconductor device according to claim 2, characterized in that the intermediate layer is one atomic layer.
34. The semiconductor device according to claim 3, characterized in that the intermediate layer is one atomic layer.
35. The semiconductor device according to claim 2, characterized in that the thickness of the intermediate layer is 100 nm or smaller.
36. The semiconductor device according to claim 3, characterized in that the thickness of the intermediate layer is 100 nm or smaller.
37. The semiconductor device according to claim 2, characterized in that the first polar face is the (0001) Si polar face of 4H-, 6H- or 15R-SiC or the (111) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (0001) Si polar face or the (111) Si polar face is no larger than 10 degrees.
38. The semiconductor device according to claim 3, characterized in that the first polar face is the (0001) Si polar face of 4H-, 6H- or 15R-SiC or the (111) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (0001) Si polar face or the (111) Si polar face is no larger than 10 degrees.
39. The semiconductor device according to claim 2, characterized in that the first polar face is the (0001) Si polar face of 4H-, 6H- or 15R-SiC or the (111) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (0001) Si polar face or the (111) Si polar face is no larger than 10 degrees.
40. The semiconductor device according to claim 3, characterized in that the first polar face is the (0001) Si polar face of 4H-, 6H- or 15R-SiC or the (111) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (0001) Si polar face or the (111) Si polar face is no larger than 10 degrees.
41. The semiconductor device according to claim 3, characterized in that the first polar face is the (0001) Si polar face of 4H-, 6H- or 15R-SiC or the (111) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (0001) Si polar face or the (111) Si polar face is no larger than 10 degrees, and the second polar face is the (000-1) nitrogen or O (oxygen) polar face of a group III nitride layer or a group II oxide layer, or a face the deviation of which in a plane direction from the (000-1) face is no larger than 10 degrees.
42. The semiconductor device according to claim 3, characterized in that the first polar face is the (000-1) C polar face of 4H-, 6H- or 15R-SiC or the (-1-1-1) Si polar face of 3C-SiC, or a face the deviation of which in a plane direction from the (000-1) C polar face or the (-1-1-1) Si polar face is no larger than 10 degrees, and the second polar face is the (0001) group III or group II polar face of a group III nitride layer or a group II oxide layer, or a face the deviation of which in a plane direction from the (0001) face is no larger than 10 degrees.
Type: Application
Filed: Mar 25, 2008
Publication Date: Mar 25, 2010
Applicant:
Inventors: Jun Suda (Kyoto), Tsunenobu Kimoto (Kyoto)
Application Number: 12/450,424
International Classification: H01L 29/24 (20060101); G02B 6/10 (20060101);